Aspirin (acetylsalicylic acid) and certain closely related compounds are the most commonly used therapeutic drugs in the world. The drug has a very short half life after administration and is rapidly metabolized to salicylic acid (hereafter called salicylate). Although generally recognized as safe, plasma salicylate levels of 30mg/dl and above may be toxic, with levels exceeding 40mg/dl sometimes being fatal. Since therapeutic levels of aspirin for the treatment of rheumatoid arthritis are usually in the range from 20-30mg/dl, it is desirable to be able to monitor the dosage of aspirin in order to assure that the plasma salicylate levels are in an effective but safe range.
Heretofore, plasma salicylate monitoring has usually been accomplished by either colorimetric methods or by high pressure liquid chromatography. Each of these techniques can be difficult and time-consuming. It would therefore be desirable to provide the compounds necessary to perform immunoassays for the determination of salicylate in plasma. 2. Description of Prior Art
Antibodies to aspirin and related compounds have been described by Wicher, et al. (1968) J. Immunol. 101:342-348, and Hoffman and Campbell (1969) J. Immunol. 103:655-661. Singh et al., Anal. Biochem. (1980) 104:51-58 describe the use of a methyldithioacetic acid and bromoacetylglycine combination for linking gentamicin to glucose-6-phosphate dehydrogenase.